SYNTHESIS OF FRAGMENTS OF TRANSFORMING GROWTH-FACTOR-ALPHA INCORPORATING EXO-2-AZABICYCLO[2,2,1]HEPTANE-3-CARBOXYLIC ACIDS AS PROLINE SUBSTITUTES

Two novel amino acids, the enantiomers of exo 2-azabicyclo[2,2,1]hepta ne-3-carboxylic acid have ben independently synthesized by the aza Die ls Alder reaction using a chiral auxiliary. The two acids have been ad vanced via solid phase synthesis to afford linear sequences, which hav e been cyclized to afford cyclic disulfide peptides, analogues of frag ments of TGF alpha. The structures of these and other fragments have b een firmly established.